Xtenex, “indeXed-TENsioning-NEXus” is actually the mechanics of employing varying degrees of tension, in this case along the length of a shoelace, between the eyelets.
Other laces tend to slip, relaxing the tension needed for a good fit. Xtenex laces are elastic shoelaces, and use uniformly spaced knots to modify the levels of tension as needed.
Once these laces are fitted into the eyelets and tied up, your shoe becomes like a loafer, you really don’t have to tie and untie every time you wear the shoe.